This invention relates to a communication control unit and a filtering method in a communication control unit and in particular to a communication control unit and a filtering method for controlling the start, end, and change of an interactive communication session as a control function of a plurality of communication terminals for each unit (domain) of an IP (Internet Protocol) network formed by connecting communication terminals in conformity with the Internet protocol to a LAN.
Demand for a communication control unit rises steadily from integration of an intracorporate communication infrastructure into an IP base and the rise of VoIP (Voice over IP). Malicious calls and an increase in traffic load are easily possible problems and a technique of regulating them (filtering) is a surely important function.
In the filtering in the current IP communications, first a filtering system based on filtering considering originator/receipt party as one set is known. That is, it is a system for refusing a message from an originator with an undesired incoming with the receipt party as the subject. In the system in the related art, for example, the originator IP address and receipt party IP address information is referenced from the header part of the received IP packet and a filter table is searched for entries and if the corresponding entry is found, the IP packet is discarded (or is passed through).
However, the filter table involves a problem of being incapable of setting based on time specification. JP-2002-232453 discloses an Internet protocol filtering apparatus, etc., for making it possible to control an IP packet flow in a network for each predetermined time by setting an entry in a filter table so as to apply filtering only within a specific time. (For example, refer to JP-A-2002-232453.)
Second, a filtering system for regulating messages from other than registered users is known. Whether or not the user is a registered user is determined by the identifier for uniquely indicating the user (for example, identifier of IP address, etc.). For example, “an inter-terminal communication connection control method using an IP transfer network” for performing IP packet filtering is disclosed wherein an address management table is provided in a communication control unit and only an IP packet with a pair of IP address and port number registered in the table is allowed to pass through. (For example, refer to JP-A-2002-314577.) As is obvious from the description given above, as the filtering methods in the related arts, IP and transport layer filtering techniques are general.
A system for also enabling a receipt party to set filtering as a client function is disclosed. (For example, refer to JP-A-8-251231.) A document describes unsolicited bulk e-mail filtering for stopping mail service distribution based on the mail address of the user transmitting more than a predetermined number of pieces of mail if mail is transmitted to an indefinite number of persons indiscriminately or in large quantity. (For example, refer to JP-A-2003-87327.) A system is also disclosed wherein URLs and telephone numbers in unsolicited bulk e-mail text are extracted for storage and whether or not mail sent to the mail user contains any of the stored URLs and telephone numbers is determined, whereby unsolicited bulk e-mail can be filtered if the mail address of the destination is changed. (For example, refer to JP-A-2003-263391.) A system for performing session open control in accordance with the number of sessions that can be opened for each group concerning TSS (time sharing system) sessions is disclosed. (For example, refer to JP-A-3-52055.)